Central pontine myelinolysis is a rare non-inflammatory affection of the cerebral white matter, which usually occurs in the central part of the pons. Extrapontine localisations are less common. A low plasmatic sodium concentration and more often its rapid correction to normal values, are assumed to be the most important etiopathogenic features. Chronic alcoholism is associated with many cases. Clinical manifestations include various degrees of spastic tetraparesis, pseudobulbar palsy and altera- tion of consciousness. Magnetic resonance (MR) imaging shows a well defined lesion in the central part of the pons, hyperintense in T2 and hypointense in T1 weighted images. The authors report the case of a young alcoholic patient developing the typical picture of central pontine myelinolysis in spite of normal sodium plasma values. Surprisingly, only moderate clinical signs contrasted with an extensive involvement of the pons, visible on MR. Two successive MR investigations, 1.5 months and 5 months later, showed identical radiological findings. The neurological state of the patient, however, was almost normal at the time of MR imaging. Clinical and neuroanatomical correlation and discrepancies are discussed in detail.

        Key words: central pontine myelinolysis, magnetic resonance imaging, natraemia